Third Universal Definition of Myocardial Infarction

Association of Fitness in Young Adulthood With Survival and Cardiovascular Risk: The Coronary Artery Risk Development in Young Adults (CARDIA) Study

IMPORTANCE

Although cardiorespiratory fitness (CRF) is prognostic in older adults, the effect of CRF during early adulthood on long-term cardiovascular structure, function, and prognosis is less clear.

OBJECTIVE

To examine whether CRF in young adults is associated with long-term clinical outcome and subclinical cardiovascular disease (CVD).

DESIGN, SETTING, AND PARTICIPANTS

Prospective study of 4872 US adults aged 18 to 30 years who underwent treadmill exercise testing at a baseline study visit from March 25, 1985, to June 7, 1986, and 2472 individuals who underwent a second treadmill test 7 years later. Median follow-up was 26.9 years, with assessment of obesity, left ventricular mass and strain, coronary artery calcification (CAC), and vital status and incident CVD. Follow-up was complete on August 31, 2011, and data were analyzed from recruitment through the end of follow-up.

MAIN OUTCOMES AND MEASURES

The presence of CAC was assessed by computed tomography at years 15 (2000-2001), 20 (2005-2006), and 25 (2010-2011), and left ventricular mass was assessed at years 5 (1990-1991) and 25 (with global longitudinal strain). Incident CVD and all-cause mortality were adjudicated.

RESULTS

Of the 4872 individuals, 273 (5.6%) died and 193 (4.0%) experienced CVD events during follow-up. After comprehensive adjustment, each additional minute of baseline exercise test duration was associated with a 15% lower hazard of death (hazard ratio [HR], 0.85; 95% CI, 0.80-0.91; P < .001) and a 12% lower hazard of CVD (HR, 0.88; 95% CI, 0.81-0.96; P = .002). Higher levels of baseline CRF were associated with significantly lower left ventricular mass index (β = -0.24; 95% CI, -0.45 to -0.03; P = .02) and significantly better lobal longitudinal strain (β = -0.09; 95% CI, -0.14 to -0.05; P < .001) at year 25. Fitness was not associated with CAC. A 1-minute reduction in fitness by year 7 was associated with 21% and 20% increased hazards of death (HR, 1.21; 95% CI, 1.07-1.37; P = .002) and CVD (HR, 1.20; 95% CI, 1.06-1.37; P = .006), respectively, along with a more impaired strain (β = 0.15; 95% CI, 0.08-0.23; P < .001). No association between change in fitness and CAC was found.

CONCLUSIONS AND RELEVANCE

Higher levels of fitness at baseline and improvement in fitness early in adulthood are favorably associated with lower risks for CVD and mortality. Fitness and changes in fitness are associated with myocardial hypertrophy and dysfunction but not CAC. Regular efforts to ascertain and improve CRF in young adulthood may play a critical role in promoting cardiovascular health and interrupting early CVD pathogenesis.

Individual variability in cardiac biomarker release after 30 min of high-intensity rowing in elite and amateur athletes

This study had two objectives: (i) to examine individual variation in the pattern of cardiac troponin I (cTnI) and N-terminal pro-brain natriuretic peptide (NT-proBNP) release in response to high-intensity rowing exercise, and (ii) to establish whether individual heterogeneity in biomarker appearance was influenced by athletic status (elite vs. amateur). We examined cTnI and NT-proBNP in 18 elite and 14 amateur rowers before and 5 min, 1, 3, 6, 12, and 24 h after a 30-min maximal rowing test. Compared with pre-exercise levels, peak postexercise cTnI (pre: 0.014 ± 0.030 μg·L–1; peak post: 0.058 ± 0.091 μg·L–1; p = 0.000) and NT-proBNP (pre: 15 ± 11 ng·L–1; peak post: 31 ± 19 ng·L–1; p = 0.000) were elevated. Substantial individual heterogeneity in peak and time-course data was noted for cTnI. Peak cTnI exceeded the upper reference limit (URL) in 9 elite and 3 amateur rowers. No rower exceeded the URL for NT-proBNP. Elite rowers had higher baseline (0.019 ± 0.038 vs. 0.008 ± 0.015 μg·L–1; p = 0.003) and peak postexercise cTnI (0.080 ± 0.115 vs. 0.030 ± 0.029 μg·L–1; p = 0.022) than amateur rowers, but the change with exercise was similar between groups. There were no significant differences in baseline and peak postexercise NT-proBNP between groups. In summary, marked individuality in the cTnI response to a short but high-intensity rowing bout was observed. Athletic status did not seem to affect the change in cardiac biomarkers in response to high-intensity exercise.

The relationship between elevated red cell distribution width and long-term outcomes among patients with atrial fibrillation

OBJECTIVES

Red cell distribution width (RDW) is associated with the incidence of atrial fibrillation (AF). The aim of this study was to evaluate the relationship between elevated RDW and long-term clinical outcomes among patients with AF.

DESIGN AND METHODS

We prospectively observed 300 consecutive patients with AF (50.3% males, mean age 62.6 ± 12.9 years) between February 2009 and October 2011. Baseline RDW levels and clinical data were collected. The primary clinical outcomes of interest included all-cause mortality and the incidence of major adverse events (MAEs).

RESULTS

During a median follow-up period of 3.2 years, 60 deaths and 92 MAEs were recorded. From the lowest to the highest RDW quartile, an increased risk of mortality (2.76, 3.98, 8.40 and 13.77 per 100 person-years, respectively) and an incidence of MAEs (6.46, 8.18, 13.79 and 20.27 per 100 person-years, respectively) were noted. In a multivariate Cox regression analysis, RDW was independently associated with both all-cause mortality (hazard ratio (HR): 1.024; 95% confidence interval (CI): 1.012-1.036, P < 0.001) and MAEs (HR: 1.012; 95% CI: 1.002-1.023, P = 0.023). A receiver operating characteristic (ROC) analysis revealed that RDW predicted both mortality and MAEs with areas under the ROC curves (AUCs) of 0.682 (P < 0.001) and 0.617 (P = 0.001); the best cutoff points were 13.85% and 13.55%, respectively.

CONCLUSIONS

Elevated RDW is an independent predictor of long-term adverse clinical outcomes, including all-cause mortality and MAEs, among patients with AF.

Optimal cut-off value for cardiac troponin I in ruling out Type 5 myocardial infarction

OBJECTIVES

The clinical classification of myocardial infarction (MI) into five types was introduced in 2007 as a component of the universal definition. A Type 5 MI was defined as a MI related to coronary artery bypass surgery. In a setting of patients undergoing elective coronary artery bypass grafting, we set out (i) to describe the pattern of multiple serial cardiac troponin I (cTnI) measurements within 72 h postoperatively and (ii) to determine the optimal cardiac troponin I cut-off value in ruling in or ruling out a Type 5 MI.

METHODS

In 2011-2012, patients with two- and three-vessel disease scheduled for elective on-pump coronary artery bypass grafting were considered. Samples for cTnI were drawn before and 0, 2, 4, 6, 12, 24, 48 and 72 h after surgery. Analysis for cardiac troponin I was performed by use of the Abbott Architect c16000 system with an upper reference limit (URL) of 30 ng/l. The diagnosis of a Type 5 MI was prospectively made by a consultant cardiologist and was based on clinical, electrocardiographic and imaging data together with routine sampling and measurements of cTnI, but without knowledge of the results of serial study cTnI measurements.

RESULTS

Of the 141 eligible patients, 99 (70%) qualified for final enrollment. In 8 patients (8%), the clinical diagnosis of a Type 5 MI was made. Patients without Type 5 MI (n = 91) had a median cTnI peak value of 7675 ng/l compared with 20 500 ng/l in Type 5 MI patients (P = 0.01). By use of receiver operating characteristic curves, optimal cut-off values for identifying Type 5 MI were defined as 7970 ng/l (corresponding to 266 times the URL) 12 h postoperatively and 9950 ng/l (corresponding to 331 times the URL) 24 h postoperatively. These cut-off values resulted in negative predictive values of 0.99 (12 h) and 0.99 (24 h). Positive predictive values were 0.23 (12 h) and 0.35 (24 h).

CONCLUSIONS

In clinically stable patients undergoing elective coronary artery bypass grafting, measurements of cTnI are useful in ruling out a Type 5 MI.

[Reperfusion delays in acute coronary syndromes with ST segment elevation (STEMI) depending on prehospital care]

INTRODUCTION

Acute coronary syndrome with ST segment elevation (STEMI) remains a major cause of morbidity and mortality in France, directly correlated with the time management of the patient to achieve reperfusion of the artery as early as possible. But the delay of reperfusion is related to the course that will take the patient to the revascularization.

METHODS

To make an observation of departmental practices, we conducted a retrospective monocentric study on the STEMI supported on 4years in the Departmental Hospital of La Roche-sur-Yon by comparing the time of reperfusion in two groups: patients who used the recommended chain=diRect chain (Call the emergency number-specialist mobile emergency unit-Cardiac intensive care unit or cardiac catheterization laboratory), and patients who used another chain=Long chain.

RESULTS

On 838 patients with STEMI, 356 (42.5%) used the Direct chain. The average time of reperfusion in the Direct chain group is 4.26hours (±3.12), 6.17hours (±4.82) in the Long chain group. There is a significant difference between the two groups of 1.9hours (P<0.001). Of 186 patients who consulted a general practitioner, 40.3% of patients were not supported by the mobile emergency unit.

CONCLUSION

These results should lead to improved practices, to carry on continuing medical education with all actors in the chain and patient information to shorten up the time of reperfusion.

Glycogen phosphorylase isoenzyme BB plasma kinetics is not related to myocardial ischemia induced by exercise stress echo test

BACKGROUND

Glycogen phosphorylase BB (GPBB) is released from cardiac cells during myocyte damage. Previous studies have shown contradictory results regarding the relation of enzyme release and reversible myocardial ischemia. The aim of this study was to determine the plasma kinetics of GPBB as a response to the exercise stress echocardiographic test (ESET), and to define the relationship between myocardial ischemia and enzyme plasma concentrations.

METHODS

We studied 46 consecutive patients undergoing ESET, with recent coronary angiography. In all patients, a submaximal stress echo test according to Bruce protocol was performed. Concentration of GPBB was measured in peripheral blood that was sampled 5 min before and 10, 30 and 60 min after ESET.

RESULTS

There was significant increase of GPBB concentration after the test (p=0.021). Significant increase was detected 30 min (34.9% increase, p=0.021) and 60 min (34.5% increase, p=0.016) after ESET. There was no significant effect of myocardial ischemia on GPBB concentrations (p=0.126), and no significant interaction between sampling intervals and myocardial ischemia, suggesting a similar release profile of GPBB in ischemic and non-ischemic conditions (p=0.558). Patients in whom ESET was terminated later (stages 4 or 5 of standard Bruce protocol; n=13) had higher GPBB concentrations than patients who terminated ESET earlier (stages 1, 2 or 3; n=33) (p=0.049). Baseline GPBB concentration was not correlated to any of the patients' demographic, clinical and hemodynamic characteristics.

CONCLUSIONS

GPBB plasma concentration increases after ESET, and it is not related to inducible myocardial ischemia. However, it seems that GPBB release during ESET might be related to exercise load/duration.

Current applications of cardiac troponin T for the diagnosis of myocardial damage

Biochemical markers of myocardial injury play an important role in the diagnosis of cardiovascular diseases. Measurement of cardiac biomarkers is one of the most important diagnostic tests in acute myocardial infarction (AMI), heart failure, and other cardiovascular disorders. Recently, the European Society of Cardiology, the American College of Cardiology Foundation, the American Heart Association, and the World Heart Federation have published a consensus definition of AMI that includes a detailed guideline for the assessment of biochemical markers in suspected disease. The cardiac troponins (cTI and cTnT) were recommended as preferred markers of myocardial necrosis in this setting. Herein, we review cardiac troponin biochemistry, the performance characteristics of cTnT assays, and optimal utilization of troponin in patients with proven or possible cardiovascular disease. We also discuss the use of troponin tests, with emphasis on cTnT, in different clinical situations in which its levels may be elevated.

Obstructive sleep apnea and acute myocardial infarction severity: ischemic preconditioning?

BACKGROUND

Obstructive sleep apnea (OSA) is characterized by intermittent hypoxia (IH). In animal models, IH has been shown to protect the myocardium during periods of ischemia by reducing infarct size. However, this phenomenon of "ischemic preconditioning" has not been investigated among OSA patients with acute myocardial infarction (MI). This study investigates the role of OSA on MI severity as measured by cardiac enzymes, specifically troponin-T, among patients with an acute MI.

METHODS

This is an observational cohort study of patients ≥18 years of age who were hospitalized with an acute MI. Each participant underwent portable sleep monitoring (Apnea Link Plus); OSA was defined as an apnea-hypopnea index ≥5/h. Multivariable regression analysis was conducted to assess the relationship between OSA and highly sensitive troponin-T levels.

RESULTS

In our entire cohort of acute MI patients (n = 136), 77 % of the sample had evidence of sleep disordered breathing, with 35 % of the sample having OSA (i.e., an AHI >5). Higher AHI was associated with lower peak troponin-T levels in partially adjusted models (β = -0.0320, p = 0.0074, adjusted for age, gender, and race) and fully adjusted models (β = -0.0322, p = 0.0085) (additionally adjusted for smoking, hypertension, hyperlipidemia, body mass index, history of prior cardiovascular or cerebrovascular disease, diabetes and baseline admission creatinine levels). The mean value of the log-transformed peak troponin-T variable was used to dichotomize the outcome variable. In both partially (OR 0.949, CI 0.905-0.995, p = 0.03) and fully adjusted (OR 0.918, CI 0.856-0.984, p = 0.0151) logistic regression models, the OR for AHI suggests a protective effect on high troponin-T level.

CONCLUSIONS

Our study demonstrates that patients with OSA have less severe cardiac injury during an acute non-fatal MI when compared to patients without OSA. This may suggest a cardioprotective role of sleep apnea during acute MI via ischemic preconditioning.